This section provides background information related to the present disclosure which is not necessarily prior art.
Traditionally, engine components for automotive applications have been made of metals, such as steel and iron. Metals components are robust, typically having good ductility, durability, strength and impact resistance. While metals have performed as acceptable engine components, they have a distinct disadvantage in being heavy and reducing gravimetric efficiency, performance and power of a vehicle thereby reducing fuel economy of the vehicle.
Weight reduction for increased fuel economy in vehicles has spurred the use of various lightweight metal components, such as aluminum and magnesium alloys as well as use of light-weight reinforced composite materials. While use of such lightweight materials can serve to reduce overall weight and generally may improve fuel efficiency, issues can arise when using such materials in an engine assembly due to high operating temperatures associated with the engine assembly. For example, the lightweight metal components can also have relatively high linear coefficients of thermal expansion, as compared to traditional steel or ceramic materials. In engine assemblies, the use of such lightweight metals can cause uneven thermal expansion under certain thermal operating conditions relative to adjacent components having lower linear coefficients of thermal expansion, like steel or ceramic materials, resulting in separation of components and decreased performance. Additionally, lightweight reinforced composite materials may have strength limitations, such as diminished tensile strength, and they can degrade after continuous exposure to high temperatures. Thus, lightweight engine assemblies having increased durability under high temperature operating conditions are needed to further improve efficiency of operation and fuel economy. In particular, lightweight reciprocating components, such as crankshaft assemblies, are needed because reciprocating components can significantly affect economy and performance because of their effect on rotational momentum of inertia.